The present invention relates to a process for producing lactones. In particular, the present invention relates to a process for producing lactones in a high yield by reacting a diol, formaldehyde and carbon monoxide in the presence of a catalyst under around atmospheric pressure.
1,4-Dioxan-2-one, 1,4-dioxepan-2-one and derivatives of them produced by reacting ethylene glycol or 1,3-propanediol with formaldehyde and carbon monoxide are hopeful as starting materials for absorbable sutures or wound healing compounds. However, these lactones are usually difficultly available on the market.
A production process according to the disclosure of U.S. Pat. No. 4,070,375 is not always easy, because carbon monoxide of a pressure as high as 140 atm must be subjected to the reaction in highly corrosive hydrogen fluoride. Further this process requires high costs of the equipment and operation, because a highly anticorrosive pressure vessel is necessitated as the production apparatus.
Under these circumstances, the development of a process wherein the pressure of carbon monoxide to be reacted is lowered or a process wherein a less expensive apparatus is used has been eagerly demanded.